1. Field of the Invention
The present invention relates to a card connector mounted on electronic devices, such as cellular phones, telephones, PDAs (personal digital assistants), portable audio devices and cameras, and more specifically to a card connector which keeps a retainer fitting for a compression coil spring from being dislocated and thereby prevents the compression coil spring forming a card eject mechanism from coming out of the card connector even when a molded base plate of the connector is deformed as the card connector is performed a reflow-soldering to a printed circuit board of the electronic device.
2. Description of the Related Art
In electronic devices such as cellular phones, telephones, PDAs and cameras, a variety of functions are added by inserting an IC card with a built-in CPU or memory IC, such as a SIM (subscriber identity module) card, an MMC (multimedia card), an SD (secure digital) card, a Memory Stick (tradename) and a Smart Media (tradename).
Many of the card connectors mounted on such electronic devices have an eject mechanism for removing an inserted card from the connector.
A conventional card connector will be explained by referring to FIGS. 5A and 5B. FIG. 5A is a schematic plan view of the card connector with its cover removed. FIG. 5B is a cross section taken along the line VB—VB of FIG. 5A.
The card connector 100 comprises a base plate 102 and a cover 103. At least the base plate 102 is formed from an insulating material of synthetic resin. The base plate 102 is provided with a plurality of contact terminals 107 to be brought into electrical contact with a plurality of electrode pads 112 arranged on a back surface of an IC card 111. The contact terminals 107 each have a spring portion 108 for contact with the associated electrode pad 112 of the IC card 111 and a terminal portion 109 soldered to an associated contact pad of the printed circuit board of the electronic device.
The card connector 100 has a push-push type card eject mechanism 101 along one side of the base plate 102. The card eject mechanism 101 includes an eject member 104 having a card engagement portion 110, a compression coil spring 105 for pushing the eject member 104 against a stopper 113 provided on the base plate 102 when the IC card 111 is not loaded, a heart cam 114 formed on the base plate 102, lever guide grooves 115 formed along and on both sides of the heart cam 114 to guide one end of a cam lever 106, and the cam lever 106 having its one end slide along the lever guide groove 115 and the other end secured to the eject member 104.
The card eject mechanism 101 is held between the stopper 113 of the base plate 102 at one end and a retainer fitting 116 press-fitted into a rear plate 117 of the base plate 102 at the other end.
In this card eject mechanism 101, when the IC card 111 is inserted into the card connector 100, the eject member 104 is pushed by the IC card 111 through the card engagement portion 110 toward a rear side of the card connector 100 against the force of the compression coil spring 105. At this time, one end of the cam lever 106 slides in one of the lever guide grooves 115 along the heart cam 114 and becomes locked by a recessed locking portion of the heart cam 114. As a result, the IC card is held immovable in the card connector 100, with the electrode pads 112 of the IC card 111 in contact with the contact terminals 107 of the card connector 100, thus electrically connecting the IC card 111 to the card connector 100.
When the card is to be ejected, a user slightly pushes the inserted IC card 111 toward the rear. This unlocks the cam lever 106 from the locking portion of the heart cam 114. As the result, the compression coil spring 105 forces the free end portion of the cam lever 106 to move through the other lever guide groove 115 along the heart cam 114 toward the front of the card connector. Thus the eject member 104 moves toward the front of the card connector 100, pushing the IC card 111 toward the front with the card engagement portion 110 and ejecting it from the card connector 100. (For details of the card eject mechanism, refer to Japanese Patent Application Laid-open Nos. 2000-251024 and 251025.)
In the card connector 100 of the construction described above, the terminal portions 109 of the contact terminals 107 are soldered to the contact pads of the printed circuit board of an electronic device. In recent years, this solder connection is realized by a reflow soldering because of the ease with which it can be processed.
The reflow soldering is done at an elevated temperature to melt the solder. Conventional card connectors are allowed a sufficient thickness so that the base plate, though made from resin, has adequate strength to withstand high-temperature processing. In recent years, however, there are growing demands for reduced size, thickness and weight of the card connectors. And the construction of the base plate forming the card connector is being stretched to its limit in terms of shape and size.
Under these circumstances, in a construction of the card connector in which the card eject mechanism pushed by the compression coil spring is held by the retainer fitting press-fitted in the resin base plate and by the stopper formed on the resin base plate, as in the conventional card connectors, since the card connector is subjected to high temperatures when the reflow soldering is performed, the resin base plate is easily deformed by heat and thus the force of the compression coil spring may dislocate the retainer fitting, resulting in the compression coil spring flying out of the card connector.